ULA announces new date for historic Boeing Starliner launch scrubbed for mechanical issues

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Following a scrub of Monday night's Starliner launch, officials have announced a new target date for the crewed mission. The National Aeronautics and Space Administration's Boeing Crew Flight Test is now targeted to launch no earlier than 6:16 p.m. on May 17. Monday's scrub came about two hours before launch time, and officials cited the cause as a mechanical issue involving "a liquid oxygen self-regulating solenoid relief valve on the Centaur upper stage."Following a thorough data review on Tuesday, United Launch Alliance decided to replace a pressure regulation valve on the liquid oxygen tank on the Atlas V rocket's Centaur upper stage. To make this replacement, ULA will need to roll the rocket with Boeing's Starliner spacecraft back to its Vertical Integration Facility at Cape Canaveral Space Force Station. According to ULA, this rollback will begin on Wednesday. The ULA team says they will also perform leak and functional checks in support of the next launch attempt. According to officials, it was "oscillating" behavior in the valve during prelaunch operations that resulted in the scrub. While the vehicle is reliable, officials say launch parameters are different because there are humans on board. "I think that if a satellite was onboard this rocket, it might be in orbit right now. But there's no reason to make bad choices and risk anything on a test flight that has some level of risk associated with it," explained Dr. Don Platt, with Florida Tech.While a valve might seem small on a large rocket system that has cost billions to develop, it's critical for mission safety for it to be working properly, according to Platt."It's probably a few thousand dollars. The problem with this valve is that it makes sure that the oxygen tank does not build up so much pressure, so that the tank could burst. The last thing that you want is an oxygen tank bursting on flight," Platt said. "It's good that they've isolated it down to this particular valve, and they know what's wrong, and they can just go back to the hanger, if you will, and fix it." NASA veteran astronauts Butch Wilmore and Suni Williams — who will be the first humans to launch aboard Starliner — were already suited up in the Boeing pressure suits and were just about done with the process of strapping into their seats when the scrub was announced.Now, they will remain quarantined in crew headquarters at NASA until the new launch opportunity on May 17. The purpose of this mission is to test the Starliner spacecraft and its subsystems, including maneuvering and docking, before NASA can certify the spacecraft for rotational missions.